The present invention relates to method and material for forming a pattern, and more particularly, it relates to a method for forming a resist pattern, used for forming a semiconductor device or a semiconductor integrated circuit on a semiconductor substrate, by using exposing light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band and a pattern formation material used in the method.
Currently, in fabrication of a mass storage semiconductor integrated circuit, such as a 64 Mbit dynamic random access memory (RAM) and a logic device or a system LSI with a 0.25 xcexcm through 0.15 xcexcm rule, a resist pattern is formed by using a chemically amplified resist material including a polyhydroxystyrene derivative and an acid generator as principal constituents with KrF excimer laser (of a wavelength of a 248 nm band) used as exposing light.
Moreover, for fabrication of a 256 Mbit DRAM, a 1 Gbit DRAM or a system LSI with a 0.15 xcexcm through 0.13 xcexcm rule, a pattern formation method using, as exposing light, ArF excimer laser lasing at a shorter wavelength (of a 193 nm band) than the KrF excimer laser is now under development.
The chemically amplified resist material including a polyhydroxystyrene derivative as a principal constituent has high absorbance against light of a wavelength of a 193 nm band because of an aromatic ring included therein. Therefore, exposing light of a wavelength of a 193 nm band cannot uniformly reach the bottom of a resist film, and hence, a pattern cannot be formed in a good shape. Accordingly, the chemically amplified resist material including a polyhydroxystyrene derivative as a principal constituent cannot be used when the ArF excimer laser is used as the exposing light.
Therefore, a chemically amplified resist material including, as a principal constituent, a polyacrylic acid derivative or a polycycloolefin derivative having no aromatic ring is used when the ArF excimer laser is used as the exposing light.
On the other hand, as exposing light for a pattern formation method capable of coping with high resolution, X rays, an electron beam (EB) and the like are being examined.
When the X rays are used as the exposing light, however, there are a large number of problems in the exposure system and preparation of a mask. Also, when the EB is used as the exposing light, the throughput is disadvantageously low, and hence, the EB is not suitable to mass production. Thus, neither the X rays nor the EB is preferred as the exposing light.
Accordingly, in order to form a resist pattern finer than 0.10 xcexcm, it is necessary to use exposing light of a wavelength shorter than that of the ArF excimer laser, such as Xe2 laser (of a wavelength of a 172 nm band), F2 laser (of a wavelength of a 157 nm band), Kr2 laser (of a wavelength of a 146 nm band), ArKr laser (of a wavelength of 134 nm band), Ar2 laser (of a wavelength of a 126 nm band) and soft-X rays (of a wavelength of a 13, 11 or 5 nm band). In other words, a resist pattern is required to be formed by using exposing light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band.
Therefore, the present inventors have formed resist patterns by conducting pattern exposure using F2 laser (of a wavelength of a 157 nm band) on resist films formed from conventionally known chemically amplified resist materials respectively including a polyhydroxystyrene derivative represented by Chemical Formula A, a polyacrylic acid derivative represented by Chemical Formula B and a polycycloolefin derivative represented by Chemical Formula C. 
However, none of the resist patterns can be formed in a rectangular cross-sectional shape, and much scum remains on the semiconductor substrates. Such problems occur not only in using the F2 laser as the exposing light but also in using another light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band.
Accordingly, a resist pattern cannot be practically formed by irradiating a resist film formed from a conventional chemically amplified resist material including a polyhydroxystyrene derivative, a polyacrylic acid derivative or a polycycloolefin derivative with light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band.
In consideration of the aforementioned conventional problems, an object of the invention is forming a resist pattern in a good pattern shape with minimally producing scum by using exposing light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band.
The present inventors have studied the causes of the conventional problems occurring in using a conventional resist material, such as a resist material including a polyhydroxystyrene derivative as a principal constituent, and have found the following:
First, the resist material including a polyhydroxystyrene derivative has high absorbance against light of a wavelength of a 1 nm through 180 nm band. For example, a resist film with a thickness of 100 nm formed from the resist material has transmittance of 20% at most against a F2 laser beam (of a wavelength of a 157 nm band).
Therefore, various examination has been made on means for improving the transmittance of a resist material against light of a wavelength of a 1 nm through 180 nm band. As a result, the transmittance of a resist film against light of a wavelength of a 1 nm through 180 nm band can be improved when a novel siloxane skeleton having a steric structure is introduced into a base polymer of the resist material as compared with the case where a linear or ladder siloxane skeleton is introduced.
Also, it has been found that when a siloxane skeleton having a steric structure is introduced into the base polymer, the refractoriness of an unexposed portion of the resist film in a developer can be improved.
Moreover, it has been found that when a siloxane skeleton having a steric structure is introduced into the base polymer, the dry etching resistance and the heat resistance of the resist film can be improved.
The present invention was devised on the basis of the aforementioned findings, and specifically, the invention provides the following pattern formation material and pattern formation methods.
The pattern formation material of this invention comprises a base polymer which is a siloxane compound represented by Chemical Formula 1: 
wherein R1 are the same or different compounds selected from the group consisting of an alkyl compound, an ester compound, an ether compound, a sulfone compound, a sulfonyl compound and an aromatic compound.
In the pattern formation material of this invention, the siloxane compound represented by Chemical Formula 1 has a siloxane skeleton with a steric structure. Therefore, the absorbance against light of a wavelength of a 1 nm through 180 nm band can be lowered as compared with that of a siloxane compound having a linear or ladder siloxane skeleton. Accordingly, the transmittance against light of a wavelength of a 1 nm through 180 nm band of the base polymer can be improved. As a result, when pattern exposure is carried out on a resist film formed from the pattern formation material of this invention by using exposing light of a wavelength of a 1 nm through 180 nm band, a resist pattern can be formed in a rectangular cross-sectional shape.
Furthermore, when a siloxane skeleton with a steric structure is introduced into the base polymer, the refractoriness of an unexposed portion of the resist film in a developer can be improved without changing solubility of an exposed portion in the developer. Therefore, no scum is produced on the substrate as well as the resolution (the contrast between the exposed portion and the unexposed portion) of the resist film can be improved.
Moreover, when a siloxane skeleton with a steric structure is introduced into the base polymer, the dry etching resistance and the heat resistance of the resist film can be also improved.
Preferably, the pattern formation material further comprises an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 1 is an alkyl compound represented by Chemical Formula 2: 
wherein R2 is a protecting group released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
Preferably, the pattern formation material further comprises an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 1 is an alkyl compound represented by Chemical Formula 3: 
wherein R3 are the same or different protecting groups released by an acid.
Preferably, the pattern formation material further comprises an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 1 is an ether compound represented by Chemical Formula 4: 
wherein R4 is a protecting group released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
Preferably, the pattern formation material further comprises an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 1 is an ether compound represented by Chemical Formula 5: 
wherein R5 is a protecting group released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
The first pattern formation method of this invention comprises the steps of forming a resist film by applying, on a substrate, a pattern formation material containing a base polymer which is a siloxane compound represented by Chemical Formula 6: 
wherein R1 are the same or different compounds selected from the group consisting of an alkyl compound, an ester compound, an ether compound, a sulfone compound, a sulfonyl compound and an aromatic compound; irradiating the resist film with exposing light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band for pattern exposure; and forming a resist pattern by developing the resist film after the pattern exposure.
In the first pattern formation method, since the siloxane compound represented by Chemical Formula 6 has a siloxane skeleton with a steric structure, the absorbance against light with a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band can be lowered as compared with that of a siloxane compound with a linear or ladder siloxane skeleton. Therefore, the transmittance against light of a 1 nm through 30 nm band or a 110 nm through 180 nm band of the resist film can be improved, resulting in forming a resist pattern in a rectangular cross-sectional shape.
Furthermore, scum is not produced on the substrate during the formation of the resist pattern and the resolution of the resist film can be improved. Therefore, the resist pattern can be formed in a good pattern shape.
Moreover, the dry etching resistance and the heat resistance of the resist film can be improved.
In the first pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 6 is preferably an alkyl compound represented by Chemical Formula 7: 
wherein R2 is a protecting group released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
In the first pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 6 is preferably an alkyl compound represented by Chemical Formula 8: 
wherein R3 are the same or different protecting groups released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
In the first pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 6 is preferably an ether compound represented by Chemical Formula 9: 
wherein R4 is a protecting group released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
In the first pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 6 is preferably an ether compound represented by Chemical Formula 10: 
wherein R5 is a protecting group released by an acid.
Thus, a chemically amplified resist film with high resolution, high dry etching resistance and high heat resistance can be formed in a good pattern shape without producing scum.
The second pattern formation method of this invention comprises the steps of forming an organic film from an organic compound on a substrate; forming a resist film by applying, on the organic film, a pattern formation material containing a base polymer which is a silixoane compound represented by Chemical Formula 11: 
wherein R1 are the same or different compounds selected from the group consisting of an alkyl compound, an ester compound, an ether compound, a sulfone compound, a sulfonyl compound and an aromatic compound; irradiating the resist film with exposing light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band for pattern exposure; forming a resist pattern by developing the resist film after the pattern exposure; and forming an organic film pattern by conducing dry development using oxygen plasma on the organic film with the resist pattern used as a mask.
In the second pattern formation method, since the siloxane compound represented by Chemical Formula 11 has a siloxane skeleton with a steric structure, the absorbance against light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band can be lowered as compared with that of a siloxane compound with a linear or ladder siloxane skeleton. Therefore, the transmittance against light of a wavelength of a 1 nm through 30 nm band or a 110 nm through 180 nm band of the resist film can be improved. As a result, a mask pattern including the resist pattern and the organic film pattern can be formed in a rectangular cross-sectional shape.
Furthermore, no scum is produced on the organic film during the formation of the resist pattern as well as the resolution, the dry etching resistance and the heat resistance of the resist film can be improved, resulting in forming a mask pattern with a good pattern shape.
In the second pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 11 is preferably an alkyl compound represented by Chemical Formula 12: 
wherein R2 is a protecting group released by an acid.
In the second pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 11 is preferably an alkyl compound represented by Chemical Formula 13: 
wherein R3 are the same or different protecting groups released by an acid.
In the second pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 11 is preferably an ether compound represented by Chemical Formula 14: 
wherein R4 is a protecting group released by an acid.
In the second pattern formation method, the pattern formation material preferably further contains an acid generator for generating an acid through irradiation with light, and at least one R1 of Chemical Formula 11 is preferably an ether compound represented by Chemical Formula 15: 
wherein R5 is a protecting group released by an acid.
In the first or second pattern formation method, the exposing light is preferably F2 excimer laser, Ar2 excimer laser or soft-X rays.